Dixons Carphone has revealed a major breach of data involving unauthorised access to 5.9 million customers cards and 1.2 million personal records.

The consumer electronics retailer said it was investigating an attempt to compromise the cards in a processing system at Currys PC World and Dixons Travel, but said there was no evidence of fraud as a result of the incident.

In a second breach, personal data such as name, address or email addresses, have been accessed. Again, Dixons said there was no evidence that it had resulted in fraud.

Of the 5.9 million cards that were accessed illegally, 5.8 million were chip and pin protected, and no pin codes, card verification values (CVV) or authentication data were accessed, meaning purchases could not be made.

However, about 105,000 payment cards from outside the EU and without chip and pin protection were accessed. The retailer said it had notified the banks concerned and they had not detected any fraudulent purchases on customer accounts.